As a method for sealing an electronic device, known is a method of sealing the electronic device with a resin sheet.
For example, Patent Documents 1 and 2 each disclose a method of: arranging a resin sheet on an electronically functional element (such as a SAW filter) mounted on a substrate; next putting, into a bag having gas barrier performance, the electronically functional element on the substrate, and the resin sheet; next reducing the pressure in the bag; and next sealing the electronically functional element in the bag with the resin sheet. This method has advantages that the SAW filter can be sealed under the reduced pressure to decrease the generation of voids, and that the method can be performed through a simple pressure decreasing apparatus.